RELATIONSHIP BETWEEN PECTIN-METHYL ESTERASE ACTIVITY AND SOFTENING IN ‘RAF’ TOMATO FRUIT

‘Raf’ tomato has a higher organoleptic quality than many current cultivars, but it has very short shelf-life, is susceptible to chilling and mechanical injury during postharvest handling.
Moreover, in this climacteric fruit ripening processes occur rapidly, particularly colour change.
The softening of the fruit is due to the action of several enzymes, such as pectinmethyl esterase (PME) and polygalacturonase which play a joint role in this process.
This paper studies the relationship between PME activity and softening of the fruits.
Fruits harvested at the turning stage were stored at room temperature (24°C) for 4 days or 4°C for 28 days, until they reached the red-ripe stage.
Colour, firmness and PME activity were determined.
The data show that the fruits turned red in about 24 hours, as the tristimulus parameter (a) increased from -3 to +8. The firmness of the fruit declined progressively during the 4 days of storage, and PME activity also declined gradually, showing a high correlation between shelf life (time storage) and activity of PME enzyme.
However, this correlation is not so marked between PME activity and fruit softening, suggesting that PME is not the only enzyme involved in this process.

XXVIII International Horticultural Congress on Science and Horticulture for People (IHC2010): International Symposium on Postharvest Technology in the Global Market

M. Guzmán, A. Sánchez , M.C. Salas, F. del Moral, J.L. Valenzuela

pectin methyl esterase, firmness, softening, tomato

https://doi.org/10.17660/ActaHortic.2012.934.175